(1) Field of the Invention
The present invention pertains to a hydra-jack screw apparatus used to exert a force against an object, to vary the magnitude of the force exerted against the object, and to provide a visual indication of the magnitude of the force applied against the object. The hydra-jack screw apparatus of the invention may be used in a variety of environments where it is desired to adjust a force exerted on an object, and be provided with a visual indication of the magnitude of force exerted on the object.
(2) Description of the Related Art
In many applications where a screw is used to exert a force against an object by turning the screw through a complementary threaded hole in a stationary member adjacent the object, it is desirable to be able to adjust the force exerted on the object and to be provided with some indication of the force exerted on the object. Just one example of such an environment is in the jack screws of a rotary die cutting press.
Most conventional die cutting presses include as part of the press two or more jack screws. The jack screws adjust the pressure or force exerted by the rotating cutting die of the press against a web of stock material passed between the rotating cutting die and the anvil roll of the press. The jack screws of the press are tightened down by the press operator to force the cutting die toward the anvil roll and increase the cutting force of the rotating die against the web of stock material, causing the cutting edges of the die to cut deeper through the stock material. The jack screws of the press are backed out of their complementary screw threaded holes to reduce the force exerted by the rotating cutting die on the web of stock material and decrease the depth of the cuts in the stock material produced by the cutting edges of the die.
Such an adjustment of the jack screws is necessary in order for the press to be used in a variety of cutting operations. In some cutting operations it may be desired to cut completely through the material, while in other operations it may be desired to only cut through a first layer of a multi-layered material. The cuts made through the material by the cutting die are monitored by the press operator to ensure that a uniform pressure is exerted across the rotating cutting die during the operation of the press. It is necessary that a uniform pressure be exerted across the rotating cutting die in order for the press to produce consistent cuts of the desired depth through the web material passed through the press.
To assist the operator, some prior art presses are provided with gauge assemblies that provide the operator with a visual indication of the magnitude of force exerted by the cutting die across the width of the stock material being cut. However, in many applications of jack screws a pressure monitoring gauge is not provided with the machine in which the jack screws are used. In such situations a separate pressure gauge must be used to provide the operator of the jack screws with some visual indication of the force being exerted by the jack screws as they are adjusted.
What is needed is a single apparatus that can be used to exert a force against an object, and can be used to adjust the force exerted against the object, and also simultaneously provides a visual indication of the force exerted against the object as that force is adjusted.